Three basic methods are known to protect a facility from lightning strokes:
1) Prevent the stroke by discharging the cloud induced charge on the earth's surface. PA0 2) Isolating a site by creating a space charge of the opposite polarity thereby preventing the stroke. PA0 3) Wait for the stroke, and bypass the stroke current through a lightning rod into the earth.
The most advanced stroke prevention system is described in Carpenter's U.S. Pat. No. 4,180,698 issued Dec. 25, 1979. Thousands of ionizer points are suspended over the protected facility. These points are grounded to an underground current collector which surrounds the protected facility. The site or facility is discharged before the stroke occurs.
The most widely accepted lightning rod configurations are described in Underwriters Laboratories, Standard for Lightning Protection Components: UL 96, Third Edition and NFPA Standard 78. Tubular metal air terminals are described having terminal base supports which are connected to a common ground wire.
The air terminals described in UL 96 do not offer any stroke prevention capabilities and are limited in their collecting capability to no better than plus or minus 45 degrees. They merely bypass the stroke down a preferred path and minimize the damage. They are, however, relatively inexpensive and easy to install. What has been needed in the marketplace is an inexpensive UL approved lightning terminal which gives the resulting assembly a reasonable level of lightning prevention capability and a more effective collection capability. The present invention addresses those needs.